Question

The sum of the digits of a two-digit number is 3. If the digits are reversed, the new number increased by 3 is twice the original number. Then the original number is: (a) 12 (b) 30 (c) 21 (d) none of these ​

Answer 1

Answer:

let the digit at unit place of the two digit num be X

then,

Accourding to Q

tense place digit=3-x

so,

original num=X+10 (3-x)

= x +30-10X

= 30-9x

on reversing the num

once place digit=3-X

tens Place digit=X

so, new num=3-x+10x = 3+9x

Accourding to question,

2( original num) = 3+new num

=> 2 (30-9x) = 3+3+9x

=>60-18x=6+9x

=>60-6=9x+ 18x

=>54=27x

so, X=2

So, original num=30-9X

30-9X2

= 30-18

= 12

so, option (a) is correct